We propose to develop a community AIDS risk behavior surveillance and monitoring system and to assess an expanded and continuous preventive intervention program to detect under what circumstances two intervention modalities are effective in reducing or changing risk behaviors and maintaining behaviors that protect IV drug users and crack users from HIV infection. The assumption that guides this prevention project is that intervention, in order to be effective must be sensitive but aggressive and not solely dependent on compliant help seeking. The proposed project is conceptualized as a continuous care intervention that started with the interventions of the Puerto Rico AIDS Prevention Project (PRAPP). In order to determine the distribution of high risk drug use and sexual behaviors related to HIV transmission, as well as maintaining changes in these behaviors, a surveillance and monitoring system will collect data from 4,050 IVD and crack users. Participants of the intervention research trial will consist of 600 participants of the previous PRAPP Project, and 900 new IVD and crack users randomly selected from the monitoring and surveillance sample during the five year period of the study. The intervention program adds two intervention components to our previous PRAPP intervention, the Skill Assessment Encounter (control group) and the Social Context Encounter (experimental group). Study subjects will be randomly assigned to each intervention component. The Project will be a coordinating endeavor between the Department of Anti-Addiction Services, the Puerto Rico Health Department and the AIDS Institute. The Project will work through two assessment centers strategically situated in catchment areas of the Metropolitan Area of San Juan, the city with the highest prevalence of drug use and HIV in the island. Data analysis of the monitoring phase of the project will focus on the distribution and trends in risk behaviors in Puerto Rico. The process evaluation will document the effectiveness of the procedures used to carry out the project, the degree to which the original design was followed, problems encountered, and how they were resolved. Analysis of variance as well as regression techniques will be used to assess the effectiveness of the interventions. Multiple regression, using logistic and analysis of variance techniques will be used to examine the effect of background variables and the main and interactive effect of the experimental conditions.